Recently, electric vehicles which are less in harmful exhaust emission and eco-friendly, such as electric drive vehicles (EV) and plug-in hybrid electric vehicles (PHEV) have been put on the market. Further, vehicular power supply devices for charging, or charging-discharging on storage batteries of electric vehicles are gradually spreading.
As shown in FIG. 7, a vehicular power supply device for charging electric vehicles includes a power converter 101 (charger) for outputting charge power to charge a storage battery B2 included in an electric vehicle C2, and an output terminal of the power converter 101 is connected to a first end of an electric cable 102. A second end of the electric cable 102 is connected to a connector 103, and this connector 103 is to be removably connected to an inlet 104 provided to the electric vehicle C2.
Further, the power converter 101 supplies charge power to the storage battery B2 of the electric vehicle C2 through the electric cable 102 and the connector 103.
Note that, there has been proposed the CHAdeMO standard for DC charging systems for electric vehicles, and the CHAdeMO standard defines an interface shown in FIG. 8.
The electric cable 102 in conformity with the CHAdeMO standard includes two power supply lines Wp101 and Wp102 for supplying charge power, five analog lines Wa101 to Wa105, and two CAN communication lines Wc101 and Wc102.
The power converter 101 and the electric vehicle C2 are connected by way of the electric cable 102. Note that, a circuit ground of the power converter 101 and a circuit ground of the electric vehicle C2 are interconnected with the analog line Wa105.
FIG. 9 is arrangement of pins of the connector 103 corresponding to the power supply lines Wp101 and Wp102, the analog lines Wa101 to Wa105, and the CAN signal lines Wc101 and Wc102. In FIG. 9, the pins Pp101 and Pp102 correspond to the power supply lines Wp101 and Wp102 respectively, the pins Pa101 to Pa105 correspond to the analog lines Wa101 to Wa105 respectively, and the pins Pc101 and Pc102 correspond to the CAN signal lines Wc101 and Wc102 respectively.
The power converter 101 includes a diode D101 connected in series with an output terminal for charge power.
The electric vehicle C2 includes a vehicle-side breaker M100 for allowing or prohibiting supply of charge power to the storage battery B2 through the power supply lines Wp101 and Wp102. When a control relay 211 is turned on or off, the vehicle-side breaker M100 is excited or not excited, and thereby is turned on or off.
The power converter 101 generates a control voltage Vcc10 (DC 12 V), and this control voltage Vcc10 is supplied to the electric vehicle C2 through a relay 201 of the power converter 101 and the analog line Wa101.
While the control relay 211 of the electric vehicle C2 is turned on, the control voltage Vcc10 operates the vehicle-side breaker M100. When the control voltage Vcc10 is supplied from the power converter 101 to the electric vehicle C2, the vehicle-side breaker M100 is turned on (closed).
While the power converter 101 and the electric vehicle C2 are not interconnected by the electric cable 102, the drive power is not supplied to the vehicle-side breaker M100, and therefore a contact device is not turned on.
A charging flow is started when the power converter 101 accepts charge operation conducted by a user.
The power converter 101 which has accepted the charge operation turns on the relay 201, and thus the control voltage Vcc10 is supplied from the power converter 101 to the electric vehicle C2 through the analog line Wa101, and this leads to excitation of a photocoupler PC21.
As a result, the electric vehicle C2 acknowledges that the charge operation has been started, and transmits parameters including maximum voltage and battery capacity of the storage battery B2 to the power converter 101 via CAN (Controller Area Network) communication by way of the CAN signal lines Wc101 and Wc102.
The power converter 101 sends data including maximum output voltage and maximum output current to the electric vehicle C2 via CAN communication.
The electric vehicle C2 checks compatibility of the power converter 101, and subsequently turns on a transistor Tr21 to excite the photocoupler PC11 of the power converter 101, thereby sending a notice of start of charging to the power converter 101 through the analog lines Wa104.
The power converter 101 acknowledges that charge is allowed by the electric vehicle C2, and then locks the connector 103 to the inlet 104 and performs insulation test for detecting abnormality such as short circuiting and ground fault. After completion of the insulation test, the power converter 101 turns on a relay 202 to excite the photocoupler PC22 of the electric vehicle C2, thereby sending, to the electric vehicle C2 through the analog line Wa102, a notice that charge is ready.
In the electric vehicle C2, the control relay 211 is turned on and thereby the vehicle-side breaker M100 is turned on. Thereafter, the electric vehicle C2 sends a chargeable maximum current value to the power converter 101 via CAN communication every 0.1 seconds.
The power converter 101 performs constant current control to supply charge current with a value equal to the maximum current value.
During charging, the electric vehicle C2 monitors a state of the storage battery B2 and a value of charge current. When abnormality is detected, supply of charge current can be stopped.
When detecting abnormality, the electric vehicle C2 stops supply of charge current by:
(1) sending, to the power converter 101 via CAN communication, instructions to set an output current to zero;
(2) sending an error signal to the power converter 101 via CAN communication,
(3) turning off the transistor Tr21 to send an analog signal indicative of prohibiting of charge to the power converter 101; and
(4) turning off the control relay 211 to turn off the vehicle-side breaker M100.
Additionally, the power converter 101 also monitors currents, voltages, and temperatures of circuits thereof. When any of the currents, the voltages, and the temperatures exceeds a limited value, the power converter 101 sends an error signal to the electric vehicle C2 via CAN communication, thereby stopping supply of charge power.
At the time of end of charge, instructions to set current to zero are sent from the electric vehicle C2 to the power converter 101 via CAN communication. After the charge current becomes zero, the vehicle-side breaker M100 is turned off. Further, the electric vehicle C2 turns off the transistor Tr21, thereby outputting an analog stop signal to the power converter 101.
The power converter 101 confirms that the output current is zero, and then turns off the relays 201 and 202.
When the connector 103 of the power converter 101 is connected to the inlet 104 of the electric vehicle C2, a control voltage Vcc20 generated by the electric vehicle C2 causes a flow of an analog signal for connector connection confirmation in the analog line Wa103. The analog signal for connector connection confirmation excites a photocoupler PC23 of the electric vehicle C2, and therefore the electric vehicle C2 can confirm that the connector 103 is connected to the inlet 104.
Further, as shown in FIG. 10, the power converter 101 includes a ground fault detector 101b provided to an AC power line on an input side of the electric conversion circuit 101a performing AC/DC conversion, and a ground fault detector 101c provided to a DC power line on an output side of the electric conversion circuit 101a. 
Not only when ground fault of the AC power line is detected but also when ground fault of the DC power line is detected, the power converter 101 separates the output terminal for charge power, and thus safety is ensured.
Note that, there has been proposed other charge systems for electric vehicles in conformity with the Combo standard. An electric cable of the Combo standard includes two power supply lines for supplying AC charge power, other two power supply lines for supplying DC charge power, and three analog lines for transmitting control signals.
FIG. 11 is arrangement of pins of a connector 203 of the Combo standard. Pins Pp201 and Pp202 correspond to the two power supply lines for supplying AC charge power. Pins Pp203 and Pp204 correspond to the two power supply lines for supplying DC charge power. Pins Pa201 to Pa203 correspond to the analog lines.
As described above, there have been proposed various methods for the charge systems of electric vehicles. Additionally, there has been proposed a configuration in which a connector-side breaker is provided in a connector so as to break power supply paths even when welding in a vehicle-side breaker is caused by some factors (e.g., see document 1 [JP 2013-31348 A]).
In the aforementioned document 1, when charge current becomes excess due to short circuiting or the like, the connector-side breaker is turned off and thereby the power supply paths are broken. In summary, the configuration disclosed in document 1 is not for turning off the connector-side breaker in response to abnormality of electric vehicles. Therefore, even if abnormality occurs in the electric vehicle and this leads to welding in the vehicle-side breaker, the configuration disclosed in document 1 fails to turn off the connector-side breaker.